The invention relates to incandescent lamp and glass reflector combinations for use in projection systems such as 16 mm. movie projectors.
In known projection units which include a preformed glass reflector and projection lamp (e.g. tungsten halogen) therein, the lamp is retained in alignment with the reflector by employing a suitable cement (e.g. sauereisen) within the reflector and about the lamp's sealed end. Examples of such arrangements are shown in U.S. Pat. Nos. 3,314,331 (Wiley) and 3,639,750 (Anthonijsz). Use of cement or a similar permanent-type bonding agent prohibits separation of the lamp and reflector in the event that replacement of either of these components is necessary. In almost all cases, it is only the incandescent lamp which fails and needs replacement.
The aforementioned permanent bond between lamp and glass reflector was heretofore believed essential to assure precise alignment between said components and between these members and other elements (e.g. film gate, projection lens) within the overall system. Alignment between reflector and lamp was usually achieved using a precisioned instrument whereupon the assembled unit was ready for insertion within a respective socket-holder arrangement, such as shown in U.S. Pat. No. 3,789,212 (Wagner). This latter positioning is usually accomplished by the projector's operator.
Required replacement of both lamp and reflector therefor results in an unnecessary waste of material which in turn adds appreciably to the overall cost of operating the system.
It can therefore be seen that a projection unit which permits removal of the lamp from the unit's glass reflector to in turn permit replacement of only the lamp while still assuring the precisioned alignment between lamp and reflector and lamp-reflector and other elements of the system would constitute a significant advancement in the art.